Neutron dose detection apparatus and neutron capture therapy device

ABSTRACT

Disclosed are a neutron dose detection apparatus and a neutron capture therapy device. The neutron dose detection apparatus includes at least two counting rate channels and a counting rate channel selection unit used for selecting one of the at least one counting rate channels. The counting rate channel includes a detector used for detecting neutrons and outputting a signal, a signal processing unit used for processing the signal output by the detector, and a counter used for counting the signal output by the signal processing unit.

CROSS-REFERENCE TO RELATED PATENT APPLICATION

This application is a continuation application of InternationalApplication No. PCT/CN2021/104172, filed on Jul. 2, 2021, which claimspriority to Chinese Patent Application No. 202010631538.8, filed on Jul.3, 2020, and Chinese Patent Application No. 202011060387.1, filed onSeptember 30, the disclosures of which are hereby incorporated byreference.

TECHNICAL FIELD

The disclosure relates to the field of radioactive ray irradiation, andin particular to a neutron dosage detection apparatus and a neutroncapture therapy device.

BACKGROUND

The background description provided herein is for the purpose ofgenerally presenting the context of the disclosure. Work of thepresently named inventors, to the extent it is described in thisbackground section, as well as aspects of the description that may nototherwise qualify as prior art at the time of filing, are neitherexpressly nor impliedly admitted as prior art against the disclosure.

With the development of atomics, radio therapy, such as cobalt sixty, alinear accelerator, an electron beam, or the like, has become one of themajor means to treat cancers. However, traditional photon or electrontherapy is restricted by physical conditions of radioactive raysthemselves, and thus will also harm a large number of normal tissues ona beam path while killing tumor cells. Furthermore, owing to differentlevels of sensitivity of tumor cells to radioactive rays, traditionalradiotherapy often has poor treatment effect on malignant tumors (forexample, glioblastoma multiforme and melanoma) with radio resistance.

In order to reduce radiation injury to normal tissues around tumors, atarget therapy concept in chemotherapy is applied to radiotherapy. Withrespect to tumor cells with high radio resistance, irradiation sourceswith high relative biological effectiveness (RBE), such as protontherapy, heavy particle therapy, neutron capture therapy, or the like,are also developed actively now. Here neutron capture therapy combinesthe abovementioned two concepts, for example, boron neutron capturetherapy. By means of specific aggregation of boron-containing drugs intumor cells and cooperating with precise neutron beam control, a cancertreatment choice better than traditional radioactive rays is provided.

During the boron neutron capture therapy, an irradiation dosage appliedto a sick body needs to be controlled accurately due to stronger neutronbeam radioactive rays performing radiotherapy on the sick body. However,when a therapy plan is formulated, there are still problems ofinaccurate setting of preset irradiation parameters, such as a neutronirradiation dosage, and inaccurate detection of an actual irradiationdosage.

Furthermore, during an actual irradiation, an event that an instructionis input by mistake or relevant instructions and irradiation parametersare changed occurs occasionally, due to a fact that an operator or adoctor accidentally touches a control panel by mistake, so that amedical risk is increased.

SUMMARY

In order to solve the above problems, the disclosure provides a neutrondosage detection apparatus and a neutron capture therapy device capableof applying an accurate neutron irradiation dosage to a sick body. Theneutron dosage detection apparatus includes at least two counting ratechannels and a counting rate channel selection unit configured to selectone of the at least two counting rate channels, the counting ratechannel includes a detector configured to detect a neutron and output asignal, a signal processing unit configured to process the signal outputfrom the detector, and a counter configured to count a signal outputfrom the signal processing unit to obtain a counting rate.

Further, the counting rate channels may include at least a firstcounting rate channel including a first detector and a second countingrate channel including a second detector, and sensitivity of the firstdetector is different from sensitivity of the second detector.

Further, a charged particle beam accelerated by an accelerator mayundergo a nuclear reaction with a target to generate the neutron, andthe counting rate channel selection unit may select the counting ratechannel according to power of the accelerator, a neutron beam flux, or adistance between the detector and a neutron source.

Further, the neutron dosage detection apparatus may further include aconversion unit configured to convert a counting rate recorded by thecounting rate channel into a neutron flux rate or a neutron dosage rate,the counting rate channel is selected by the counting rate channelselection unit, and an integration unit configured to integrate theneutron flux rate or the neutron dosage rate to obtain a neutron dosage.

Further, the neutron dosage detection apparatus may further include adisplay configured to display the neutron dosage.

Further, the counting rate channels may include: a first counting ratechannel including a first detector configured to detect a neutron andoutput a signal, a first signal processing unit configured to processthe signal output from the first detector, and a first counterconfigured to count a signal output from the first signal processingunit; and a second counting rate channel including a second detectorconfigured to detect a neutron and output a signal, a second signalprocessing unit configured to process the signal output from the seconddetector, and a second counter configured to count a signal output fromthe second signal processing unit, and the first detector has a firstsensitivity of detecting the neutron, the second detector has a secondsensitivity of detecting the neutron, and the first sensitivity is lessthan the second sensitivity.

Further, in response to an actual power of the accelerator being lessthan half of a maximum power, the counting rate channel selection unitmay select to transmit a counting rate recorded by the second counter ofthe second counting rate channel to the conversion unit for dosagecalculation; otherwise, the counting rate channel selection unit mayselect to transmit a counting rate recorded by the first counter of thefirst counting rate channel to the conversion unit for dosagecalculation.

Further, a neutron flux generated when the accelerator is at a maximumpower may be defined as a maximum neutron flux, and in response to areal-time neutron flux being less than half of the maximum neutron flux,the counting rate channel selection unit may select to transmit acounting rate recorded by the second counter of the second counting ratechannel to the conversion unit for dosage calculation; otherwise, thecounting rate channel selection unit may select to transmit a countingrate recorded by the first counter of the first counting rate channel tothe conversion unit for dosage calculation.

The neutron capture therapy device includes the above neutron dosagedetection apparatus.

Further, the neutron capture therapy device may further include aneutron beam irradiation system, the neutron beam irradiation systemincludes a neutron beam generation module configured to generate aneutron beam, and a beam adjustment module configured to adjust theneutron beam and including a retarder configured to decelerate theneutron beam and a reflector configured to guide a deviated neutron backto the retarder.

Further areas of applicability will become apparent from the descriptionprovided herein. It should be understood that the description andspecific examples are intended for purposes of illustration only and arenot intended to limit the scope of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate one or more embodiments of thedisclosure and together with the written description, serve to explainthe principles of the disclosure. Wherever possible, the same referencenumbers are used throughout the drawings to refer to the same or likeelements of an embodiment.

FIG. 1 is a schematic diagram of a neutron beam irradiation system of aneutron capture therapy device of the disclosure.

FIG. 2 is a schematic diagram of a beam shaping body of a neutroncapture therapy device of the disclosure.

FIG. 3 is a schematic diagram of a neutron beam irradiation system and adetection system of a neutron capture therapy device of the disclosure.

FIG. 4 is a schematic diagram of a neutron dosage detection device in afirst embodiment of a neutron capture therapy device of the disclosure.

FIG. 5 is a schematic diagram of a neutron dosage detection device in asecond embodiment of a neutron capture therapy device of the disclosure.

FIG. 6 is a schematic diagram of a monitoring system of a neutroncapture therapy device of the disclosure.

FIG. 7 is a schematic diagram of an anti-misoperation system incombination with a display part and an input part of a neutron capturetherapy device of the disclosure.

DETAILED DESCRIPTION OF THE DISCLOSURE

In order to make purposes, technical solutions and technical effects ofthe disclosure clearer and enable those skilled in the art to implementthem accordingly, the disclosure will be further described in detailbelow in combination with the accompanying drawings and embodiments.

In the following descriptions, terms “first”, “second”, or the like, maybe used here to describe various elements, but these elements are notlimited by these terms, and these terms are used to distinguish thedescribed objects without any order or technical meaning.

Radiotherapy is a common means for treating cancers, and Boron NeutronCapture Therapy (BNCT) is an effective means for treating cancers andhas been used increasingly in recent years. As shown in FIG. 1 to FIG. 7, a neutron capture therapy device irradiating a neutron beam of apreset neutron dosage an object to be irradiated, such as a sick body S,so as to perform BNCT includes a neutron beam irradiation system 1, adetection system, a monitoring system 3, a correction system and ananti-misoperation system. The neutron beam irradiation system 1 isconfigured to generate a neutron beam suitable for performing theneutron irradiation therapy on the sick body S. The detection system isconfigured to detect irradiation parameters such as a neutron dosage, orthe like, during the neutron irradiation therapy. The monitoring system3 is configured to control the whole neutron beam irradiation process.The correction system is configured to correct a preset neutron dosage.The anti-misoperation system is configured to prevent related personnelfrom inputting wrong instructions and information to the monitoringsystem 3.

BNCT produces two heavily charged particles 4He and 7Li by using acharacteristic of a boron-containing (10B) drug having a high capturesection for a thermal neutron, and through 10B(n,α)7Li neutron captureand a nuclear fission reaction. The two heavily charged particles eachhas an average energy of about 2.33 MeV, and has characteristics of highLinear Energy Transfer (LET) and a short range. The LET and range of the4He particle are 150 keV/µm and 8 µm respectively, the LET and range ofthe 7Li heavily charged particle are 175 keV/µm and 5 µm respectively,and a total range of the two heavily charged particles is approximatelyequivalent to a size of a cell, so that radiation damage to an organismmay be limited to the cell level. The boron-containing drug isselectively gathered in tumor cells. After the neutron beam enters abody of the sick body S, it undergoes a nuclear reaction with boron inthe body of the sick body S, to produce two heavily charged particles⁴He and ⁷Li, and the two heavily charged particles ⁴He and ⁷Li locallykill the tumor cells without causing too much damage to normal tissues.

As shown in FIG. 1 , the neutron beam irradiation system 1 includes aneutron beam generation module 11 and a beam adjustment module 12configured to adjust a neutron beam generated by the neutron beamgeneration module 11.

The neutron beam generation module 11 generates the neutron beamirradiated to the sick body S, and includes an accelerator 111configured to accelerate a charged particle beam, a target 112configured to react with the charged particle beam to generate theneutron beam, and a charged particle beam transport part 113 locatedbetween the accelerator 111 and the target 112 and configured totransport the charged particle beam. The charged particle beam transportpart 113 transports the charged particle beam to the target 112, and hasone end connected to the accelerator 111 and the other end connected tothe target 112. Furthermore, the charged particle beam transport part113 is provided with a beam control device, such as a beam adjustmentpart (not shown), a charged particle scanning part (not shown), or thelike. The beam adj ustment part controls a travelling direction and abeam diameter of the charged particle beam. The charged particle beamscanning part scans the charged particle beam and controls anirradiation position of the charged particle beam relative to the target112.

The accelerator 111 may be a cyclotron, a synchrotron, asynchrocyclotron, a linear accelerator, or the like. The commonly usedtarget 112 includes lithium (Li) target and beryllium (Be) target. Thecharged particle beam is accelerated to an energy sufficient to overcomeCoulomb repulsion of nuclei of the target 112 and undergoes a ⁷Li(p,n)⁷Be nuclear reaction with the target 112 to generate the neutron beam.The commonly discussed nuclear reaction includes ⁷Li(p, n)⁷Be and ⁹Be(p,n)⁹B. Usually, the target 112 includes a target layer and ananti-oxidation layer located on a side of the target layer andconfigured to prevent oxidation of the target layer, and theanti-oxidation layer is made of Al or stainless steel.

In the embodiments disclosed in the disclosure, the accelerator 111accelerates charged particles to allow them to undergo a nuclearreaction with the target 112 to supply a neutron source. In otherembodiments, the neutron source may be supplied by using a nuclearreactor, a D-T neutron generator, a D-D neutron generator, or the like.However, no matter whether the neutron source is supplied byaccelerating the charged particles to allow them to undergo the nuclearreaction with the target 112, as disclosed in the disclosure, or theneutron source is supplied by the nuclear reactor, the D-T neutrongenerator, the D-D neutron generator, or the like, a mixed irradiationfield is generated, that is, the generated beam includes a highspeedneutron beam, an epithermal neutron beam, a thermal neutron beam and agamma ray. During BNCT, the higher the content of the rest ofirradiation rays (collectively referred to as irradiation raycontamination) except for the epithermal neutron, the greater theproportion of non-selective dosage deposition in normal tissues,therefore radiation causing unnecessary dosage deposition may bereduced.

The International Atomic Energy Agency (IAEA) has given five air beamquality factor recommendations for the neutron source used by clinicalBNCT. The five recommendations may compare advantages and disadvantagesof different neutron sources, and serve as a reference for selecting aneutron generation pathway and designing a beam shaping body 121. Thefive recommendations are as follows:

-   Epithermal neutron flux > 1 × 10⁹ n/cm²s-   Fast neutron contamination < 2 × 10⁻¹³ Gy-cm²/n-   Photon contamination < 2 × 10⁻¹³ Gy-cm²/n-   Thermal to epithermal neutron flux ratio < 0.05-   Epithermal neutron current to flux ratio > 0.7

Note: an epithermal neutron has an energy region between 0.5 eV and 40keV, a thermal neutron has an energy region less than 0.5 eV, and a fastneutron has an energy region greater than 40 keV.

As shown in combination with FIG. 2 and FIG. 3 , the beam adjustmentmodule 12 is configured to adjust mixed irradiation rays generated inthe neutron beam generation module 11, so as to reduce the irradiationray contamination irradiated to the sick body S and focus an epithermalneutron for treating the sick body S to a part, needed to be irradiated,of the sick body S. The beam adjustment module 12 includes the beamshaping body 121 configured to decelerate and shield the neutron beam,and a collimator 122 configured to focus the epithermal neutron to thepart, needed to be irradiated, of the sick body S. The beam shaping body121 includes a retarder 1211 configured to decelerate the neutron beamgenerated from the target 112 to an energy region of the epithermalneutron, a reflector 1212 configured to guide a deviated neutron back tothe retarder 1211 to increase a beam intensity of the epithermalneutron, a thermal neutron absorber 1213 configured to absorb a thermalneutron to avoid excessive dosage deposition in superficial normaltissues during therapy, and a radiation shield 1214 configured to shielda leaked neutron and photon to reduce dosage deposition in normaltissues at a non-irradiated region. In other embodiments, the thermalneutron absorber may not be included, instead the thermal neutron isabsorbed by substances contained in the retarder or the reflector, or itmay be understood that the retarder and the thermal neutron absorber areintegrally provided. In other embodiments, the radiation shield may notbe included, instead the radiation shield may be made of the samematerial as the reflector, or it may be understood that the reflectorand the radiation shield are integrally provided.

The retarder 1211 may be formed by stacking multiple differentmaterials. The material of the retarder 1211 is selected according tofactors, such as energy of the charged particle beam, or the like. Forexample, when energy of a proton beam from the accelerator 111 is 30 MeVand the Be target is used, the material of the retarder 1211 is lead(Pb), iron, aluminum (Al) or calcium fluoride. When the energy of theproton beam from the accelerator 111 is 11 MeV and the Be target isused, the material of the retarder 1211 is heavy water (D₂O), or leadfluoride, or the like. As an embodiment, the retarder 1211 is formed bymixing MgF₂ and LiF which is 4.6% of MgF₂ by weight percentage, thereflector 1212 is made of Pb, and the thermal neutron absorber 1213 ismade of ⁶Li. The radiation shield 1214 includes a photon shield and aneutron shield. Here the photon shield is made of Pb and the neutronshield is made of polyethylene (PE). The retarder 1211 may be formed ina bi-conical shape as disclosed in FIG. 2 or a cylindrical shape asdisclosed in FIG. 3 . The reflector 1212 is arranged around the retarder1211, and has a shape adaptively changed according to the shape of theretarder 1211.

Continuing to refer to FIG. 3 , the detection system includes a neutrondosage detection device 21 configured to detect the neutron dosage ofthe neutron beam in real time, a temperature detection device 22configured to detect temperature of the target 112, a displacementdetection device 23 configured to detect whether the sick body Sgenerates displacement during therapy, and a boron concentrationdetection device (not shown) configured to detect the boronconcentration in the body of the sick body S.

As shown in combination with FIG. 4 , the neutron dosage detectiondevice 21 includes a detector 211 configured to receive the neutron andoutput a signal, a signal processing unit 212 configured to process thesignal output from the detector 211, a counter 213 configured to count asignal output from the signal processing unit 212 to obtain a countingrate, a conversion unit 214 configured to convert the counting raterecorded by the counter 213 into a neutron flux rate or a neutron dosagerate, an integration unit 215 configured to integrate the neutron fluxrate or the neutron dosage rate to obtain the neutron dosage, and adisplay 218 configured to display the neutron dosage. The detector 211,the signal processing unit 212 and the counter 213 form a counting ratechannel 20.

The detector 211 may be placed in the beam shaping body 121, may also beplaced in the collimator 122, or may also be arranged at any positionadjacent to the beam shaping body 121, as long as the position where thedetector 211 is located may be configured to detect the neutron dosageof the neutron beam.

The detector 211 capable of detecting the neutron dosage of the neutronbeam in real time is provided with an ionization chamber and ascintillation detector. Here a He-3 proportional counter, a BF₃proportional counter, a fission chamber, and a boron ionization chamberuse a structure of the ionization chamber as a substrate, and thescintillator detector contains an organic material or an inorganicmaterial. When the thermal neutron is detected, the scintillatordetector usually adds a high thermal neutron capture section elementsuch as Li, or B, or the like. A certain element in two types ofdetectors captures the neutron entering the detector or undergoes thenuclear fission reaction with the neutron entering the detector torelease heavily charged particles and nuclear fission fragments, whichgenerate a large number of ionization pairs in the ionization chamber orthe scintillation detector, and these charges are collected and form anelectrical signal. The signal processing unit 212 performs noisereduction, conversion and separation processing on the electricalsignal, and the electrical signal is converted into a pulse signal. Aneutron pulse signal and a γ pulse signal are distinguished by analyzinga magnitude of a voltage pulse. The separated neutron pulse signal iscontinuously recorded by the counter 213 to obtain the counting rate(n/s) of the neutron. The conversion unit 214 calculates and convertsthe counting rate through internal software, programs, or the like, toobtain the neutron flux rate (cm⁻²s⁻¹), and further calculates andconverts the neutron flux rate to obtain the neutron dosage rate (Gy/s).And the integration part integrates the neutron dosage rate to obtainthe real-time neutron dosage.

A brief introduction is made below by example of the fission chamber,the scintillator detector and the BF₃ detector.

When the neutron beam passes through the fission chamber, it dissociateswith gas molecules inside the fission chamber or a wall of the fissionchamber to generate an electron and a positively charged ion, which arereferred to as the ion pair as described above. Due to a high voltage ofan electric field applied in the fission chamber, the electron movestowards a central anode wire and the positively charged ion movestowards a surrounding cathode wall, so that a measurable electricalsignal is generated.

Substances, such as an optical fiber, or the like, in the scintillationdetector absorb energy and generate visible light, which uses ionizingradiation to excite an electron in a crystal or molecule to an excitedstate. Fluorescence emitted when the electron returns to a ground stateis collected and serves as detection of the neutron beam. The visiblelight emitted by action of the scintillation detector and the neutronbeam is converted into an electrical signal by using a photomultipliertube, to be output.

The BF₃ detector is placed in the beam shaping body 121 and configuredto receive irradiation of the neutron beam, an element B in the BF₃detector undergoes a nuclear reaction ¹⁰B(n, alpha)⁷Li with the neutron,and alpha particles generated by the nuclear reaction and ⁷Li electricparticles are collected by a high voltage electrode under driving of thevoltage, to generate an electrical signal. The electrical signal istransmitted to the signal processing unit 212 through a coaxial cable,to be subject to signal amplification, filtering and shaping, so as toform a pulse signal. The processed pulse signal is transmitted to thecounter 213, to count pulses therein, so as to obtain the counting rate(n/s) through which intensity of the neutron beam, i.e., the neutrondosage, may be measured in real time.

The temperature detection device 22 is a thermocouple, and twoconductors with different components (referred to as thermocouple wiresor hot electrodes) are connected at both ends to form a loop. Whentemperature of the connection point is different, an electromotive forcemay be generated in the loop. This phenomenon is referred to as athermoelectric effect, and the electromotive force is referred to asthermoelectric potential. The thermocouple performs temperaturemeasurement by using this principle, of which one end directlyconfigured to measure temperature of a medium is referred to as aworking end (also known as a measurement end), and the other end isreferred to as a cold end (also known as a compensation end). The coldend is connected to a display instrument or an assorted instrument, andthe display instrument may indicate the thermoelectric potentialgenerated by the thermocouple. Of course, as known by those skilled inthe art, the temperature detection device 22 may also be any detector211 capable of detecting temperature, such as a resistance thermometer,or the like.

The displacement detection device 23 is an infrared signal detector, andthe infrared detector operates by detecting infrared rays emitted by ahuman body. The infrared detector collects infrared radiation from theoutside and gathers the infrared radiation on an infrared sensor. Theinfrared sensor usually uses a pyroelectric element, which releasescharges to the outside when temperature of the infrared radiationchanges, and an alarm is generated after detecting and processingcharges. The detector 211 is aimed to detecting radiation of the humanbody. Therefore, a radiation-sensitive element is very sensitive toinfrared radiation with a wavelength of about 10 µm. Of course, it iswell known by those skilled in the art that the displacement detectiondevice 23 may be any detection device suitable for detecting change ofdisplacement of an object to be irradiated, such as a displacementsensor. The displacement sensor determines whether the object to beirradiated moves, according to the change of displacement of the objectto be irradiated relative to a certain reference object. It is also wellknown by those skilled in the art that the displacement detection device23 not only may be configured to detect the change of displacement ofthe object to be irradiated, but also may be configured to detect changeof displacement of a support member and/or a treatment table fixing theobject to be irradiated, thereby indirectly knowing the change ofdisplacement of the object to be irradiated.

During the neutron beam irradiation therapy for the sick body S, boronis continuously supplied to the sick body S as needed. A boronconcentration may be detected by an inductively coupled plasmaspectroscopy, a high-resolution α autoradiography, a charged ionspectroscopy, a neutron capture camera, a nuclear magnetic resonanceimaging and a magnetic resonance imaging, a positive electron emissiontomography, a prompt γ-ray spectroscopy, or the like, and a deviceinvolved in the above detection method is referred to as a boronconcentration detection device.

The disclosure is described by example of calculating the boronconcentration in the body of the sick body S by detecting γ-ray releasedby the sick body S. The neutron beam enters the body of the sick bodyand reacts with boron to generate γ-ray. By measuring the amount ofγ-ray, the amount of boron reacting with the neutron beam may becalculated, thereby calculating the boron concentration in the body ofthe sick body S. The boron concentration detection device is configuredto measure the boron concentration in the body of the sick body S inreal time when the neutron beam irradiation system 1 performs theneutron beam irradiation therapy on the sick body S.

The boron concentration detection device detects γ-ray (478 keV)generated by reaction between the neutron and boron, to measure theboron concentration, and a boron distribution measurement system(PG(Prompt-y)-SPECT) capable of measuring a single-energy γ-ray tomeasure distribution of the boron concentration is used as the boronconcentration detection device. The boron concentration detection deviceincludes a γ-ray detection part and a boron concentration calculationpart. The γ-ray detection part detects information related to γ-rayemitted from the body of the sick body S, and the boron concentrationcalculation part calculates the boron concentration in the body of thesick body S according to the information related to γ-ray detected bythe γ-ray detection part. The γ-ray detection part may use thescintillator and various other γ-ray detection devices. In theimplementation, the γ-ray detection part is arranged in the vicinity ofa tumor of the sick body S, for example, at a position about 30 cm awayfrom the tumor of the sick body S.

The detector 211 of the above neutron dosage detection device 21configured to detect the neutron dosage of the neutron beam belongs to apulse detector, and a shortest time interval between two consecutivelyincident neutrons distinguished by the detector 211 is described as apulse resolution time τ(s). The detector 211 may not record otherincident neutrons accurately within τtime after a neutron is incident onthe detector 211, thus it is also referred to as dead time.

Sensitivity of the detector 211 detecting the neutron is a ratio oftotal output of the detector 211 to a corresponding total input. For thedetector 211 of the neutron dosage detection device 21 exemplified inthe disclosure, the input physical quantity of the detector is theneutron beam, and its output physical quantity is usually an opticalsignal or an electrical signal. The higher the ratio of the total outputto the corresponding total input, the higher the sensitivity of thedetector 211 detecting the neutron. The higher the sensitivity ofdetecting the neutron, the shorter the pulse resolution time τcorresponding to the detector 211. Usually, in order to reduce astatistical error, the detector 211 with high sensitivity of detectingthe neutron detects a low-flux beam, and the detector 211 with lowsensitivity of detecting the neutron detects a high-flux beam.

Different embodiments are described in detail below. For simplicity, thesame component has the same digital identifier in different embodiments,and similar components are distinguished by the same digital identifierplus ‘ ′ ’ or ‘ ″ ’ in different embodiments.

In the first embodiment disclosed in FIG. 4 , the neutron dosagedetection device 21 is provided with a counting rate channel 20. Inorder to accurately detect neutron dosages of neutron beams of differentfluxes, in the second embodiment disclosed in FIG. 5 , the neutrondosage detection device 21′ includes at least two counting rate channels20′. The detector 211′ of each counting rate channel 20′ has a differentsensitivity of detecting the neutron. Further, the neutron dosagedetection device 21′ further includes a counting rate channel selectionunit 216 configured to select an appropriate counting rate channel 20′according to a current power of the accelerator 111 or a neutron beamflux. In the second embodiment, the neutron dosage detection device 21′includes at least two counting rate channels 20′, a counting ratechannel selection unit 216 configured to select an appropriate countingrate channel 20′ from the at least two counting rate channels 20′, aconversion unit 214 configured to convert a counting rate recorded bythe counting rate channel 20′ selected by the counting rate channelselection unit 216 into the neutron flux rate or the neutron dosagerate, and an integration unit 215 configured to integrate the neutronflux rate or the neutron dosage rate to obtain the neutron dosage.

The two counting rate channels 20′ are named as a first counting ratechannel 201 and a second counting rate channel 202 respectively. Thefirst counting rate channel 201 includes a first detector 2011configured to receive the neutron and output a signal, a first signalprocessing unit 2012 configured to process the signal output from thefirst detector 2011, and a first counter 2013 configured to count asignal output from the first signal processing unit 2012. The secondcounting rate channel 202 includes a second detector 2021 configured toreceive the neutron and output a signal, a second signal processing unit2022 configured to process the signal output from the second detector2021, and a second counter 2023 configured to count a signal output fromthe second signal processing unit 2022. The counting rate channelselection unit 216 selects an appropriate counting rate channel 20according to a current power of the accelerator 111 or a neutron beamflux. The conversion unit 214 converts a counting rate recorded by thecounting rate channel 20 selected by the counting rate channel selectionunit 216 into the neutron flux rate or the neutron dosage rate. Theintegration unit 215 integrates the neutron flux rate or the neutrondosage rate to obtain the neutron dosage.

Usually, a neutron flux which may be generated when the accelerator 111is at a maximum power is described as a maximum neutron flux. When adetected real-time neutron flux is less than half of the maximum neutronflux, it is considered as a small neutron flux. When the detectedreal-time neutron flux is greater than or equal to half of the maximumneutron flux, it is considered as a large neutron flux.

Sensitivity of the first detector 2011 detecting the neutron is a firstsensitivity, sensitivity of the second detector 2021 detecting theneutron is a second sensitivity, and the first sensitivity is less thanthe second sensitivity. The first detector 2011 is wrapped with a largenumber of neutron absorbing materials, such as B₄C, Cd, or is filledwith a low-pressure working gas, or is designed to be small in size,thereby reducing the sensitivity of detecting the neutron. When theneutron flux is large, the first detector 2011 is used for detection, sothat a counting rate loss caused by the pulse resolution time may bereduced. Compared with the first detector 2011, the second detector 2021is wrapped with a small number of neutron absorbing materials, or is notwrapped with any material, or is filled with a high-pressure workinggas, or is designed to be large in size, so that the second sensitivityis greater than the first sensitivity. When the neutron flux is small,the second detector 2021 is used for detection, so that a statisticalerror of a counting rate caused by a low counting rate may be reduced.

Correspondingly, the sensitivity of the first counting rate channel 201detecting the neutron is smaller than the sensitivity of the secondcounting rate channel 202 detecting the neutron. A counting rateselection unit selects an appropriate counting rate channel 20′according to a current power of the accelerator 111 or a neutron flux.For example, in the case where a maximum beam intensity of theaccelerator 111 is 10 mA, when a beam intensity of the accelerator 111is greater than 5 mA, a counting rate recorded by the first counter 2013of the first counting rate channel 201 with the first sensitivity isselected to be transmitted to the conversion unit 214 for dosagecalculation; and when a beam intensity of the accelerator 111 is lessthan 5 mA, a counting rate recorded by the second counter 2023 of thesecond counting rate channel 202 with the second sensitivity is selectedto be transmitted to the conversion unit 214 for dosage calculation. Amore accurate counting rate is selected by the counting rate selectionunit to be transmitted to the conversion unit 214 for dosagecalculation, thereby obtaining an accurate neutron irradiation dosage.

The neutron dosage detection device 21 is provided with at least twocounting rate channels with different sensitivities of detecting theneutron, i.e., the first counting rate channel 201 and the secondcounting rate channel 202, and the counting rate channel selection unit216 selects a more accurate counting rate according to an actualsituation, to calculate the neutron dosage, so that a counting rate losserror caused by the pulse resolution time may be reduced. At the sametime, a statistical error caused by a low counting rate is considered,so that accuracy of real-time neutron dosage detection is improved,thereby improving accuracy of the neutron dosage of the neutron beamirradiated to the sick body S.

In other implementations, the counting rate channels 20 and 20′ may beconfigured to be any number of counting rate channels, as needed.

Furthermore, in the implementations as exemplified above, the countingrate channel 20 is selected according to power of the accelerator 111,the neutron flux, or the like. In other implementations, the countingrate channel 20′ may be selected according to a distance between thedetector 211 and the neutron source. For example, when the detector 211is arranged at a position close to the neutron source, the secondcounting rate channel 202 with the second sensitivity is selected; andwhen the detector 211 is arranged at a position away from the neutronsource, the first counting rate channel 201 with the first sensitivityis selected.

The detector 211 of the above neutron dosage detection device 21 belongsto a pulse detector. Usually, the pulse detector has a problem ofresolution of time. An incident neutron reacts with the detector 211 togenerate a signal pulse, which may be followed by a time interval of τ.Other signal pulses generated within the time interval may be consideredas the same signal pulse by the detector 211. In this case, as long as atime interval between any two signal pulses is less than τ, the secondpulse may not be recorded. Therefore, the counting rate recorded by thecounter 213 has a deviation and is needed to be corrected. Theconversion unit 214 obtains a real-time accurate neutron flux rate andneutron dosage rate D_(t) (Gy/s) according to the corrected countingrate C_(k) in combination with the dosage conversion factor.

As shown in combination with FIG. 4 and FIG. 5 again, further, theneutron dosage detection device 21 further includes a counting ratecorrection unit 217 configured to correct the counting rate. Thecounting rate correction unit 217 includes a counting rate correctioncalculation part, a counting rate correction factor calculation part,and a pulse resolution time calculation part.

The counting rate correction calculation part calculates the correctedcounting rate C_(k) by using a formula (1-1): [0071]

C_(k) = K ⋅ C_(t)

-   where K is a counting rate correction factor; and-   Ct is a real-time counting rate recorded by the counter 213.

The counting rate correction factor calculation part calculates thecounting rate correction factor K by using a formula (1-2):

$K = \frac{n}{m}$

-   where n is the number of pulses recorded by the counter 213 in unit    time, that is, the real-time counting rate (n/s) in unit time; and-   m is the number of signal pulses actually generated within the    detector 211 in unit time, that is, the number of neutrons (n/s)    reacting with the detector 211 in unit time.

When the number of neutrons entering the detector 211 to react in unittime is m, and the number of pulses actually recorded by the counter 213in unit time is n, the time when a counter tube may not operate is nτ,and the total number of neutrons which enter the counter tube at thistime and may not be recorded is mnτ, that is, the lost count is m-n, anda formula (1-3) is obtained by derivation:

n − m = nmτ

The formula (1-3) is substituted into the formula (1-2) to obtain aformula (1-4):

$K = \frac{1}{1 - m\tau}$

It may be known from the above formula that when the pulse resolutiontime τ is known, the counting rate correction factor may be calculatedby combination of the number of pulses recorded by the counter 213 andthe formula (1-4), and the counting rate correction factor may besubstituted into the formula (1-1) to calculate the corrected countingrate.

Conventional pulse resolution time calculation methods include a doublesource method and a reactor power method. The two methods need twonatural neutron sources or reactors to calculate, and have relativelyhigh cost. Embodiments of the disclosure calculate the pulse resolutiontime based on the monitoring system of the neutron capture therapydevice, which makes full use of existing devices and resources to reducecost.

Firstly, the accelerator 111 is operated in a low flux state, and atthis time, the neutron beam flux is a first neutron beam flux I₁, andthe counting rate recorded by the counter 213 is C₁. Theoretically, dueto the low flux state, the detector 211 is not affected by the pulseresolution time and there are signal pulses which may not be recorded.The accelerator 111 is operated to a high flux state, and at this time,the neutron beam flux is a second neutron beam flux I₂, and the countingrate recorded by the counter 213 is C₂. At this time, the counting rateis affected by the pulse resolution time, so that a part of signalpulses are not recorded, and the pulse resolution time calculation partcalculates the pulse resolution time τby using a formula (1-5):

$\tau = \frac{\frac{I_{2}}{I_{1}} \cdot C_{1} - C_{2}}{\frac{I_{2}}{I_{1}} \cdot C_{1} \cdot C_{2}}$

When position of the detector 211 does not change, the pulse resolutiontime does is not needed to be calculated during operation of the deviceevery time. However, after the detector 211 operates for a long time,performance parameters of the detector 211 may change, to cause changeof the pulse resolution time, therefore the pulse resolution time isneeded to be calculated periodically.

The counting rate correction part 217 may calculate the pulse resolutiontime of the detector 211, and may calculate the counting rate correctionfactor according to the pulse resolution time, so that a counting rateerror caused by the pulse resolution time is corrected, accuracy ofreal-time neutron dosage detection is further improved, and accuracy ofthe neutron dosage of the neutron beam irradiated to the sick body S isfurther improved.

Before irradiation therapy, the total neutron dosage to be delivered tothe sick body S, the neutron flux rate or neutron dosage rate or currentduring irradiation, and the needed irradiation time, the irradiationangle and other irradiation parameters during irradiation are obtainedby simulation, calculation, or the like. For convenience of description,the above parameters are collectively referred to as preset irradiationparameters. In other embodiments, a part of or more unmentionedparameters including the above parameters may be understood as thepreset irradiation parameters, referred to as a preset neutron dosage(Gy), a preset neutron flux rate (cm⁻² s⁻¹), a preset neutron dosagerate (Gy s⁻¹), a preset current (A), a preset irradiation time (s), orthe like, respectively. During irradiation, due to change of somefactors, the irradiation parameters are needed to be adjustedperiodically according to relevant parameters detected by the detectionsystem. The irradiation parameter detected by the detection system isnamed as the real-time irradiation parameter, and the adjustedirradiation parameter is named as the corrected irradiation parameter.The adjusted irradiation parameter may be the preset irradiationparameter or the corrected irradiation parameter.

As shown with reference to FIG. 6 , the monitoring system 3 includes aninput part 31 configured to input the preset irradiation parameters, astorage part 32 configured to store the irradiation parameters, acontrol part 33 configured to perform a therapy plan according to theirradiation parameters stored in the storage part 32, a reading part 34configured to read the real-time irradiation parameters detected by thedetection system, a calculation part 35 configured to calculate thereal-time irradiation parameters and the preset irradiationparameters/the corrected irradiation parameters stored in the storagepart 32, a determination part 36 configured to determine, according to acalculation result of the calculation part 35, whether the irradiationparameters are needed to be corrected, a correction part 37 configuredto correct a part of the irradiation parameters stored in the storagepart 32 when the determination part 36 determines that the irradiationparameters are needed to be corrected, and a display part 38 configuredto display the remaining irradiation time or the remaining irradiationtime and other irradiation parameters in real time.

Before the preset irradiation parameters are corrected, the irradiationparameters stored in the storage part 32 are the preset irradiationparameters, the irradiation parameters corrected by the correction part37 are also the preset irradiation parameters, the remaining irradiationtime displayed by the display part 38 is a difference value between thepreset irradiation time and a real-time irradiation time, and theirradiation time displayed by the display part 38 is the presetirradiation time. After the preset irradiation parameters are corrected,the irradiation parameters stored in the storage part 32 are thecorrected irradiation parameters, the irradiation parameters correctedby the correction part 37 again are also the corrected irradiationparameters, the remaining irradiation time displayed by the display part38 is the corrected remaining irradiation time, and the irradiationparameters displayed by the display part 38 are the correctedirradiation parameters. Of course, the preset irradiation parameters andthe corrected irradiation parameters may also be displayed at the sametime.

In other embodiments, the input part 31, the storage part 32, or thelike, may not be included.

The monitoring system 3 is electrically connected to the detectionsystem, so that relevant information detected by the detection systemmay be transmitted to the monitoring system 3. The display 218 of theneutron dosage detection device 21 in the detection system and thedisplay part 38 of the monitoring system 3 may be the same device,usually a display screen.

Operation process of the monitoring system 3 is shown with reference toFIG. 6 , and descriptions thereof are as follows.

At S1, the preset irradiation parameters, such as a preset neutron fluxrate or a preset neutron dosage rate or a preset current, a presetneutron dosage, a preset irradiation time, a preset boron concentrationand other irradiation parameters, are input by the input part 31.

At S2, the irradiation parameters are stored by the storage part 32.

At S3, the therapy plan is performed by the control part 33 according tothe irradiation parameters stored in the storage part 32.

At S4, the real-time irradiation parameters detected by the detectionsystem are read by the reading part 34.

At S5, the irradiation parameters stored in the storage part 32 and thereal-time irradiation parameters read by the reading part 34 arecalculated by the calculation part 35.

At S6, whether the irradiation parameters stored in the storage part areneeded to be corrected, is determined by the determination part 36according to a calculation result of the calculation part 35.

At S7, latest irradiation parameters in the storage part 32 arecorrected by the correction part 37, in response to the determinationpart 36 determining that the irradiation parameters stored in thestorage part 32 are needed to be corrected; and

a correction action is not performed by the correction part 37, inresponse to the determination part 36 determining that the irradiationparameters stored in the storage part 32 are not needed to be corrected.

At S8, the remaining irradiation time or are the remaining irradiationtime and other irradiation parameters displayed by the display part 38in real time, according to the irradiation parameters stored in thestorage part 32.

During operation of the monitoring system 3, the reading part 34periodically reads the real-time irradiation parameters, for example,read the real-time irradiation parameters every 5 minutes and transmitsthe real-time irradiation parameters to the calculation part 35 forrelated calculation. In response to the difference value between thereal-time irradiation parameter and the preset irradiation parametercalculated by the calculation part 35 being greater than a firstthreshold, or in response to the real-time irradiation parameter beinggreater than a second threshold or less than a third threshold, thedetermination part 36 gives an instruction that the irradiationparameters are needed to be corrected. The correction part 37 correctsthe irradiation parameters stored in the storage part 32. On thecontrary, the determination part 36 gives an instruction that theirradiation parameters are not needed to be corrected. At this time, thecorrection part 37 does not correct the irradiation parameters stored inthe storage part 32. For example, in response to a difference valuebetween the neutron dosage rate and the preset neutron dosage ratecalculated by the calculation part 35 being greater than a preset firstthreshold, or in response to a difference value between the real-timeneutron flux rate and the preset neutron flux rate calculated by thecalculation part 35 being greater than a preset first threshold, or inresponse to a difference value between a real-time boron concentrationand the preset boron concentration calculated by the calculation part 35being greater than a preset first threshold, or in response to adifference value between the corrected remaining irradiation time andthe remaining irradiation time (a difference value between the presetirradiation time and an actually implemented irradiation time or thelast corrected remaining irradiation time) calculated by the calculationpart 35 being greater than a preset first threshold, or in response tothe calculation part 35 obtaining by comparison that the real-timeneutron dosage rate or the real-time neutron flux rate or the real-timeboron concentration is greater than a preset second threshold or lessthan a preset third threshold.

Before the preset irradiation parameters are corrected, the storage part32 stores the preset irradiation parameters, and the display part 38displays the remaining irradiation time and other preset irradiationparameters in real time. After the preset irradiation parameters arecorrected, the storage part 32 stores a latest set of correctedirradiation parameters, and the display part 38 displays the correctedremaining irradiation time and a latest set of other correctedirradiation parameters in real time. The display part 38 also displayingwhich irradiation parameters besides the remaining irradiation time, maybe selected according to actual needs. The display part 38 may displayirradiation parameters, and may also display a part of the irradiationparameters. Usually, the display part 38 displays information such asthe remaining irradiation time, the real-time irradiation dosage, theboron concentration, or the like.

In the embodiments disclosed in the disclosure, the calculation part 35combines the real-time neutron dosage D_(r) detected by the neutrondosage detection device 21 and the preset neutron dosage D_(total) inputby the input part 31, to obtain the corrected remaining irradiation timet_(r) by calculation. Here t₀ is the preset irradiation time, t is thereal-time irradiation time detected by the detection system, that is, animplemented irradiation time, is an average neutron dosage value in aperiod of t, and P is a percentage of the real-time neutron dosage tothe preset neutron dosage. P is calculated by using a formula (2-1):

$P = \frac{D_{r}}{D_{total}} \cdot 100\mspace{6mu}\%$

When P is less than 97%, the corrected remaining irradiation time t_(r)is calculated by using a formula (2-2) and a formula (2-3):

$\overline{D} = \frac{D_{r}}{t}$

$t_{r} = \frac{D_{total} - D_{r}}{\overline{D}}$

At this time, the correction part 37 is needed to correct the presetirradiation time or the corrected remaining irradiation time stored inthe storage part 32.

When P is greater than or equal to 97%, the correction part 37 adjuststhe neutron dosage rate to a first neutron dosage rate less than thepreset neutron dosage rate and increases the irradiation timecorrespondingly, to prevent the sick body S from absorbing excessiveneutrons. The first neutron dosage rate is ⅐ to ½ of the preset neutrondosage rate. Further, the neutron dosage rate is adjusted to ⅕ of thepreset neutron dosage rate I_(d), that is, the first neutron dosage rateis equal to I_(d)/5, and the corrected remaining irradiation time t_(r)is calculated by using a formula (2-4):

$t_{r} = \frac{D_{total} - D_{r}}{\frac{I_{d}}{5}}$

At this time, the correction part 37 is needed to modify the remainingirradiation time and the preset neutron dosage rate in the storage part32 to the corrected remaining irradiation time t_(r) and the correctedneutron dosage rate respectively, and the control part 33 performs thetherapy plan according to the corrected irradiation parameters. In otherimplementations, the neutron dosage rate may be adjusted to othermultiples, such as ⅓, ¼, ⅙, ⅐, or the like, of the preset neutron dosagerate, to prevent the sick body S from absorbing excessive neutrons underirradiation of the neutron beam with a high neutron dosage rate.Furthermore, the correction part 37 may adjust the neutron dosage ratewhen P is greater than or equal to 90%, or greater than or equal to 95%,or greater than or equal to other ratios, and the ratio may be presetaccording to actual situations. Of course, whether the neutron dosagerate is needed to be adjusted to the first neutron dosage rate less thanthe preset neutron dosage rate may also be determined without the valueof P calculated by the calculation part 35, instead after a conditionwhere the neutron dosage rate is needed to be corrected at whatpercentage of the real-time neutron dosage to the preset neutron dosagebased on the preset neutron dosage is determined, a threshold ismanually set and input into the storage part 32 through the input part31 for storage. When the detected real-time neutron dosage is greaterthan or equal to the threshold, the determination part 36 determinesthat the irradiation parameters are needed to be corrected, and thecorrection part 37 is enabled to adjust the neutron dosage rate to bethe first neutron dosage rate less than the preset neutron dosage rate.

In the above embodiments, when P is less than 97%, the calculation unit35 calculates an irradiation time needed to complete irradiation withthe preset neutron dosage on the premise of keeping the real-timeneutron dosage rate unchanged. In other implementations, the purpose ofcompleting the irradiation with the preset dosage within the presetirradiation time is achieved by changing the neutron dosage rate or theboron concentration while keeping the irradiation time unchanged.Methods for changing the neutron dosage rate include changing power ofthe accelerator, changing thickness of the target layer of the target112, or the like. The corrected neutron dosage rate I_(r) is calculatedby using a formula (2-5):

$I_{r} = \frac{D_{total} - D_{r}}{t_{0} - t}$

Since the neutron dosage rate is calculated from the neutron flux ratethrough the conversion factor, and the neutron flux rate is obtained byintegrating the neutron counting rate, the corrected neutron dosage rateis equivalent to the corrected neutron flux rate and the neutroncounting rate.

In the implementation, when P is greater than or equal to 97%, in orderto prevent the sick body S from absorbing excessive neutrons underirradiation of the neutron beam with a high neutron dosage rate, theneutron dosage rate is still adjusted to ⅕ of the preset neutron dosagerate, and the corrected remaining irradiation time t_(r) is calculatedby using the formula (2-4).

When the actually implemented irradiation time reaches the presetirradiation time, or when the actually irradiated neutron dosage reachesthe preset neutron dosage, the control part sends, to the neutroncapture therapy device, an instruction of stopping irradiation.

The monitoring system 3 is provided with the correction part 37 whichcorrects the irradiation parameters stored in the storage part 32 andconfigured to perform the therapy plan, therefore it is ensured that theneutron dosage of the neutron beam irradiated to the sick body isbasically consistent with the preset neutron dosage, and accuracy of theneutron dosage of the neutron beam irradiated to the sick body S isfurther improved. Furthermore, when the percentage of the real-timeneutron dosage to the preset neutron dosage is greater than or equal to97%, the neutron dosage rate is reduced and the irradiation time iscorrespondingly increased, to prevent the sick body S from absorbingexcessive neutrons under irradiation of the neutron beam with a highneutron dosage rate, which also has an effect of improving accuracy ofthe neutron dosage of the neutron beam irradiated to the sick body S.

In the implementations listed above, it may be determined, according tothe real-time neutron dosage obtained by the neutron dosage detectiondevice 21, whether the preset irradiation parameters are needed to becorrected, and the corrected irradiation parameters are calculatedaccording to the real-time irradiation parameters and the presetirradiation parameters. In other implementations, it may be determined,according to the real-time irradiation parameters detected by thetemperature detection device 22, the displacement detection device 23 orthe boron concentration detection device, whether the preset parametersare needed to be corrected, and the corrected irradiation parameters arecalculated according to the real-time irradiation parameters detected bythese detection devices. For example, when the boron concentrationdetection device detects that the boron concentration in the body of thesick body S is inconsistent with the preset boron concentration or doesnot fall within a preset range, the correction part 37 corrects theremaining irradiation time or corrects a rate of delivering boron intothe body of the sick body. Usually, it is difficult to correct the boronconcentration in the body of the sick body S in a short period of timewhen the irradiation therapy is closer to the end. At this time, theremaining irradiation time is usually selected to be corrected.

Accuracy of the irradiation dosage of the neutron beam is needed in apractical therapy. Excessive irradiation dosages may cause potentialharm to the sick body S, and too few irradiation dosages may reducequality of therapy. Both a calculation error in calculation of thepreset neutron dosage, and a deviation between the real-time irradiationparameter and the preset irradiation parameter during actual irradiationmay cause inaccurate neutron irradiation dosage. Therefore, in additionto the real-time corrected irradiation parameters, calculation of thepreset irradiation parameters is also needed during the actualirradiation. Therefore, the correction system is needed to correct thepreset neutron dosage, to ensure that the neutron irradiation dosageapplied to the sick body S is more accurate. When the preset neutrondosage of the neutron beam is corrected, the influence of factors suchas a positioning deviation of the sick body S, a real-time neutrondosage rate deviation, the boron concentration in the body of the sickbody, the neutron flux, or the like, should be considered.

A correction coefficient used by the correction system includes aneutron correction coefficient K₁ and a boron correction coefficient K₂.Here the neutron correction coefficient K₁ is related to a positioningcorrection coefficient K_(p) and a neutron beam intensity correctioncoefficient K_(i). The boron correction coefficient K₂ is related to aboron concentration correction coefficient K_(b) and a boronself-shielding effect correction coefficient K_(s).

A deviation between the real-time neutron dosage rate and the presetneutron dosage rate may directly cause a deviation of the neutron dosageirradiated to the sick body. Therefore, the positioning correctioncoefficient K_(p) and the neutron beam intensity correction coefficientK_(i) are introduced to correct the neutron irradiation dosage.

The self-shielding effect means that when there is a different boronconcentration, a track of the neutron beam irradiated into a tumor partis also different. The higher the boron concentration in the body of thesick body S, the poorer the penetrating capability of the neutron beam,the shorter the track of the neutron beam irradiated into the tumor, andthus the neutron beam may react with boron in a shallower track. On thecontrary, the longer the track of the neutron beam irradiated into thetumor, and thus the neutron beam may react with boron in a deeper track.A first boron concentration value in the body of the sick body isobtained by the boron concentration detection device, a first track ofthe neutron beam irradiated into the tumor part is provided, and thecorrection system obtains a first boron correction coefficient. A secondboron concentration value in the body of the sick body is obtained bythe boron concentration detection device, a second track of the neutronbeam irradiated into the tumor part is provided, and the correctionsystem obtains a second boron correction coefficient. Here the firstboron concentration value is greater than the second boron concentrationvalue, the first track is less than the second track, and the firstboron correction coefficient is less than the second boron correctioncoefficient. Therefore, when the neutron irradiation dosage iscalculated, the influence of the self-shielding effect on an actualirradiation effect of the neutron beam and the irradiation track of theneutron beam should be considered, thus the boron concentrationcorrection coefficient K_(b) and the boron self-shielding effectcorrection coefficient K_(s) are introduced to correct the neutronirradiation dosage.

The neutron correction coefficient K₁, the positioning correctioncoefficient K_(p) and the neutron beam intensity correction coefficientK_(i) are calculated by using a formula (3-1), a formula (3-2) and aformula (3-3) respectively, and the relevant formulas are as follows.

K₁ = K_(p) ⋅ K_(i)

$K_{p} = \frac{D}{D_{0}}$

$K_{i} = \frac{I}{I_{0}}$

-   where D is an actual therapy dosage, that is, the real-time neutron    dosage D_(r) measured by the neutron dosage detection device 21;-   D₀ is an uncorrected preset neutron dosage;-   I is an actual neutron beam intensity, that is, the real-time    neutron dosage rate measured by the neutron dosage detection device    21; and-   I₀ is a theoretical beam intensity, that is, the preset neutron    dosage rate input by the input part 31.

The boron correction coefficient K₂, the boron concentration correctioncoefficient K_(b) and the boron self-shielding effect correctioncoefficient K_(s) are calculated by using a formula (3-4), a formula(3-5) and a formula (3-6) respectively, and the relevant formulas are asfollows. [00134]

K₂ = K_(b) ⋅ K_(S)

[00135]

$K_{b} = \frac{B}{B_{0}}$

[00136]

$K_{S} = \frac{\varphi_{B}}{\varphi_{B0}}$

-   where B is an actual boron concentration in the body of the sick    body S, that is, the real-time boron concentration detected by the    boron concentration detection device;-   B₀ is a boron concentration set value in the therapy plan, that is,    the preset boron concentration input by the input part 31;-   φ_(B) is a thermal neutron flux in the body of the sick body S when    a boron concentration distribution is B; and-   φ_(B0) is a thermal neutron flux in the body of the sick body S when    a boron concentration distribution is B₀.

The uncorrected preset neutron dosage D₀ is calculated by using aformula (3-7) as follows.

D_(eq) = D_(B) ⋅ B_(con) ⋅ CBE + D_(f) ⋅ RBE_(n) + D_(th) ⋅ RBE_(n) + D_(r) ⋅ RBE_(r)

The corrected preset neutron dosage D_(total) in the therapy plan iscalculated by using a formula (3-8) as follows.

D_(total) = K₁ ⋅ (K₂ ⋅ D_(B) ⋅ B_(con) ⋅ CBE + D_(f) ⋅ RBE_(n) + D_(th) ⋅ RBE_(n) + D_(r) ⋅ RBE_(r))

-   where D_(B) is a dosage at the boron concentration of 1 ppm, and has    a unit Gy;-   B_(con) is an actually measured boron concentration, and has a unit    ppm;-   D_(f) is a fast neutron dosage, and has a unit Gy;-   D_(th) is a thermal neutron dosage, and has a unit Gy;-   RBE_(n) is a Relative Biological Effectiveness (RBE) of the neutron;-   D_(r) is a gamma dosage, and has a unit Gy; and-   RBE_(r) is a gamma RBE.

During actual therapy, the correction system corrects a preset neutrondosage in a pre-formulated therapy plan, so as to prevent applying aninaccurate neutron dosage to the sick body S.

The correction system comprehensively considers the influence of factorssuch as the positioning deviation of the sick body S, the real-timeneutron dosage rate deviation, the real-time boron concentration, or thelike on the preset neutron dosage, and introduces the neutron correctioncoefficient K₁ and the boron correction coefficient K₂ to correct thepreset neutron dosage, so that accuracy of the neutron dosage of theneutron beam irradiated to the sick body S is ensured from the source.

During actual therapy, after the input part 31 completes input of thepreset irradiation parameters, an operator starts the neutron capturetherapy device to perform irradiation therapy. After irradiation begins,the input function of the input part 31 is locked, and relevantirradiation parameters may not be input again, thus it may be ensuredthat a situation where wrong parameters and instructions are input dueto accidental touch or error operation during irradiation may beprevented. However, when the therapy process is slightly inconsistentwith an ideal state, irradiation may be stopped or continued accordingto the abnormal state, and parameters may not be corrected in time orinstructions may not be changed in time during irradiation. However,when an operation interface is simply set to be operated in real time,irradiation parameters and control instructions may still be input bythe input part 31 after irradiation begins, thus it may be ensured thatcorrect irradiation parameters and instructions may be input in realtime during irradiation. However, there is still a risk that theirradiation result is affected by inputting wrong parameters andinstructions or repeatedly inputting operation instructions due to erroroperation during irradiation.

As shown with reference to FIG. 7 , the neutron capture therapy deviceis provided with a control interface. The control interface includes theabove input part 31, the display part 38, an errorless informationconfirmation button 51, an irradiation beginning button 52, anirradiation pause button 53, an irradiation cancel button 54 and areport generation button 55. An operator activates the errorlessinformation confirmation button 51 to transmit, to the monitoring system3, a signal that information has been confirmed to be errorless. Afterthe monitoring system 3 receives the signal that information has beenconfirmed to be errorless, a condition for starting the neutron capturetherapy device for neutron beam irradiation is met. After the monitoringsystem 3 receives the signal that information has been confirmed to beerrorless, the irradiation beginning button 52 is activated, and asufficient condition for starting the neutron capture therapy device forneutron beam irradiation is met. After the neutron capture therapydevice is started, the neutron beam irradiation may be paused by theirradiation pause button 53, and the neutron beam irradiation may becancelled by the irradiation cancel button 54. After irradiation iscompleted, the report generation button 55 may be activated toautomatically generate a report related to the irradiation therapy. Whenthe neutron beam irradiation is paused, it means that the irradiationparameters and instructions are kept unchanged. By activating theirradiation beginning button 52 again, the neutron beam irradiation isperformed with original irradiation parameters and instructions. Whenthe neutron beam irradiation is cancelled, it means that the irradiationparameters and instructions are cleared. When the neutron beamirradiation is performed again, the irradiation parameters andinstructions are needed to be input again, and the errorless informationconfirmation button 51 and the irradiation beginning button 52 areactivated in sequence.

The anti-misoperation system comprehensively considers two factors ofoperability and safety, and is provided with a secondary confirmationpart and a fool-proofing part to ensure safe and precise irradiation,while the system does not lack real-time operability. Before theoperator activates the secondary confirmation part to transmit, to theneutron capture therapy device, the signal that information has beenconfirmed to be errorless, the neutron capture therapy device may not bestarted to perform the irradiation therapy plan, that is, theirradiation beginning button 52 may not be started. During starting ofthe fool-proofing part, the input part 31 which may modify and input theirradiation parameters and instructions and the report generation button55 are locked.

In the embodiments disclosed in the disclosure, the secondaryconfirmation part is the errorless information confirmation button 51 onthe control interface. Before a doctor starts a program to perform thetherapy plan, relevant information is needed to be confirmed twice.After the operator confirms that the input is errorless, and clicks theerrorless information confirmation button 51 to input, to the monitoringsystem 3, an instruction that the information is confirmed to beerrorless, the device may be started to perform the therapy plan,thereby reducing the risk of wrongly inputting wrong controlinstructions due to error operation. For example, before performingirradiation therapy on the sick body S, the doctor should checkinformation of the sick body (such as name, gender, age, or the like),irradiation parameters (such as the irradiation dosage, the collimatornumber, or the like), or the like. After checking that information iscorrect, an irradiation beginning function may be activated by clickingthe errorless information confirmation button 51 on the controlinterface. Otherwise, even though the doctor clicks the irradiationbeginning button 52, the device refuses to start neutron beamirradiation and gives a prompt that information is not confirmed.

In the embodiments disclosed in the disclosure, the fool-proofing partis the irradiation beginning button 52. After the irradiation beginningbutton 52 starts the therapy plan, the input function of the input part31 is locked and any information may not be input. Before irradiationtherapy, relevant instructions and irradiation parameters are input bythe input part 31. After relevant irradiation parameters andinstructions are input into the monitoring system 3, the operator checkswhether the relevant irradiation parameters and instructions arecorrect. After confirming that the relevant irradiation parameters andinstructions are correct, the operator activates the errorlessinformation confirmation button 51, the input part 31 may be locked, andthe relevant irradiation parameters and instructions may not be modifiedor added through the input part 31, so as to prevent wrong input. Therelevant irradiation parameters and instructions may be input againafter the input part 31 is unlocked. In the embodiments disclosed in thedisclosure, after the irradiation pause button 53 or the irradiationcancel button 54 is clicked, the irradiation therapy is stopped. At thesame time, the input part 31 configured to input relevant information isunlocked, and the relevant information may be modified or added throughthe input part 31. Of course, the input part may be automaticallyunlocked after the irradiation therapy is completed. In this way, wronginput is prevented, while operability of the system is ensured. Forexample, after checking that information of the sick body S, theirradiation parameters and other information are correct, the medicalstaff clicks the errorless information confirmation button 51 on thecontrol interface, and clicks the irradiation beginning button 52. Thesystem starts the irradiation therapy. At this time, the input part 31configured to input the relevant information is locked, and input ofinformation may not be performed.

Before the irradiation therapy is completed, the report generationbutton 55 is also locked, and after the irradiation therapy iscompleted, the report generation button 55 may be automaticallyunlocked, that is, the therapy report generation function may beenabled.

The fool-proofing part is not limited to being applied to theirradiation beginning button 52 in the above embodiment, and is alsosuitable for other buttons and parameter input windows. Furthermore, acarrier for realizing the secondary confirmation and buttonfool-proofing may be software or hardware, for example, thefool-proofing part may also be a key or a dial switch on a controlpanel. Before the key or the switch is turned on, certain operations maynot be performed, and when the key or the switch is turned on, relevantoperations may be performed.

In the embodiments disclosed in the disclosure, instructions andirradiation parameters are input by means of a touch screen. In otherimplementations, a key (for example, a mechanical key) may be used forinput.

The anti-misoperation system may not ensure functions of settingparameters and inputting control instructions if necessary, but alsoreduce wrong input of parameters or repeated input of instructions dueto error operation or other reasons, thereby reducing the risk ofoperation of the device.

In the neutron capture therapy device of the disclosure, the neutrondosage detection device 21 is provided with at least two counting ratechannels with different sensitivities of detecting the neutron, i.e.,the first counting rate channel 201 and the second counting rate channel202, and the counting rate channel selection unit 216 which selects amore accurate counting rate according to an actual situation, tocalculate the neutron dosage, so that a counting rate loss error causedby the pulse resolution time may be avoided. At the same time, astatistical error caused by a low counting rate is considered, so thataccuracy of real-time neutron dosage detection is improved, therebyimproving accuracy of the neutron dosage of the neutron beam irradiatedto the sick body S. Furthermore, the neutron dosage detection device 21is also provided with a counting rate correction unit 217 which maycalculate the pulse resolution time of the detector 211, and maycalculate the counting rate correction factor according to the pulseresolution time, so that a counting rate error caused by the pulseresolution time is corrected, accuracy of real-time neutron dosagedetection is further improved, and accuracy of the neutron dosage of theneutron beam irradiated to the sick body S is further improved.

The neutron capture therapy device of the disclosure is also providedwith the monitoring system 3. The monitoring system 3 is provided withthe correction part 37 which periodically corrects the irradiationparameters stored in the storage part 32 and configured to perform thetherapy plan, therefore it is ensured that the neutron dosage of theneutron beam irradiated to the sick body S is basically consistent withthe preset neutron dosage, and accuracy of the neutron dosage of theneutron beam irradiated to the sick body S is further improved.Furthermore, when the percentage of the real-time neutron dosage to thepreset neutron dosage is greater than or equal to 97%, the neutrondosage rate is reduced and the irradiation time is correspondinglyincreased, to prevent the sick body S from absorbing excessive neutronsunder irradiation of the neutron beam with a high neutron dosage rate,which also has an effect of improving accuracy of the neutron dosage ofthe neutron beam irradiated to the sick body S.

The neutron capture therapy device of the disclosure is also providedwith the correction system. The correction system comprehensivelyconsiders the influence of factors such as the positioning deviation ofthe sick body S, the real-time neutron dosage rate deviation, thereal-time boron concentration, or the like on the preset neutron dosage,and introduces the neutron correction coefficient K₁ and the boroncorrection coefficient K₂ to correct the preset neutron dosage, so thataccuracy of the neutron dosage of the neutron beam irradiated to thesick body S is ensured from the source.

In conclusion, the neutron capture therapy device of the disclosure mayapply an accurate neutron beam irradiation dosage to the sick body andreduce the risk of operation of the device caused by error operation onthe premise of ensuring operability of the device.

The neutron capture therapy device disclosed in the disclosure is notlimited to contents described in the above embodiments and structuresshown in the drawings. Apparent change, substitution or modificationmade for materials, shapes and positions of components therein on thebasis of the disclosure fall within the scope of protection of thedisclosure.

The foregoing description of the embodiments has been provided forpurposes of illustration and description. It is not intended to beexhaustive or to limit the disclosure. Individual elements or featuresof a particular embodiment are generally not limited to that particularembodiment, but, where applicable, are interchangeable and might be usedin a selected embodiment, even if not specifically shown or described.The same may also be varied in many ways. Such variations are not to beregarded as a departure from the disclosure, and all such modificationsare intended to be included within the scope of the disclosure.

What is claimed is:
 1. A neutron dosage detection apparatus, comprisingat least two counting rate channels and a counting rate channelselection unit configured to select one of the at least two countingrate channels, the counting rate channel comprising a detectorconfigured to detect a neutron and output a signal, a signal processingunit configured to process the signal output from the detector, and acounter configured to count a signal output from the signal processingunit to obtain a counting rate.
 2. The neutron dosage detectionapparatus of claim 1, wherein the counting rate channels comprise atleast a first counting rate channel comprising a first detector and asecond counting rate channel comprising a second detector, andsensitivity of the first detector detecting the neutron is differentfrom sensitivity of the second detector detecting the neutron.
 3. Theneutron dosage detection apparatus of claim 2, wherein a chargedparticle beam accelerated by an accelerator undergoes a nuclear reactionwith a target to generate the neutron, and the counting rate channelselection unit selects the counting rate channel according to power ofthe accelerator, a neutron beam flux, or a distance between the detectorand a neutron source.
 4. The neutron dosage detection apparatus of claim3, further comprising a conversion unit configured to convert a countingrate recorded by the counting rate channel into a neutron flux rate or aneutron dosage rate, the counting rate channel is selected by thecounting rate channel selection unit, and an integration unit configuredto integrate the neutron flux rate or the neutron dosage rate to obtaina neutron dosage.
 5. The neutron dosage detection apparatus of claim 4,further comprising a display configured to display the neutron dosage.6. The neutron dosage detection apparatus of claim 1, wherein thecounting rate channels comprise: a first counting rate channelcomprising a first detector configured to detect a neutron and output asignal, a first signal processing unit configured to process the signaloutput from the first detector, and a first counter configured to counta signal output from the first signal processing unit; and a secondcounting rate channel comprising a second detector configured to detecta neutron and output a signal, a second signal processing unitconfigured to process the signal output from the second detector, and asecond counter configured to count a signal output from the secondsignal processing unit, and the first detector has a first sensitivityof detecting the neutron, the second detector has a second sensitivityof detecting the neutron, and the first sensitivity is less than thesecond sensitivity.
 7. The neutron dosage detection apparatus of claim6, wherein in response to an actual power of the accelerator being lessthan half of a maximum power, the counting rate channel selection unitselects to transmit a counting rate recorded by the second counter ofthe second counting rate channel to the conversion unit for dosagecalculation; otherwise, the counting rate channel selection unit selectsto transmit a counting rate recorded by the first counter of the firstcounting rate channel to the conversion unit for dosage calculation. 8.The neutron dosage detection apparatus of claim 6, wherein a neutronflux generated when the accelerator is at a maximum power is defined asa maximum neutron flux, and in response to a real-time neutron fluxbeing less than half of the maximum neutron flux, the counting ratechannel selection unit selects to transmit a counting rate recorded bythe second counter of the second counting rate channel to the conversionunit for dosage calculation; otherwise, the counting rate channelselection unit selects to transmit a counting rate recorded by the firstcounter of the first counting rate channel to the conversion unit fordosage calculation.
 9. A neutron capture therapy device, comprising theneutron dosage detection apparatus of claim
 1. 10. The neutron capturetherapy device of claim 9, comprising a neutron beam irradiation system,the neutron beam irradiation system comprises a neutron beam generationmodule configured to generate a neutron beam, and a beam adjustmentmodule configured to adjust the neutron beam and comprising a retarderconfigured to decelerate the neutron beam and a reflector configured toguide a deviated neutron back to the retarder.
 11. The neutron capturetherapy device of claim 9, wherein the counting rate channels compriseat least a first counting rate channel comprising a first detector and asecond counting rate channel comprising a second detector, andsensitivity of the first detector detecting the neutron is differentfrom sensitivity of the second detector detecting the neutron.
 12. Theneutron capture therapy device of claim 11, wherein a charged particlebeam accelerated by an accelerator undergoes a nuclear reaction with atarget to generate the neutron, and the counting rate channel selectionunit selects the counting rate channel according to power of theaccelerator, a neutron beam flux, or a distance between the detector anda neutron source.
 13. The neutron capture therapy device of claim 12,further comprising a conversion unit configured to convert a countingrate recorded by the counting rate channel into a neutron flux rate or aneutron dosage rate, the counting rate channel is selected by thecounting rate channel selection unit, and an integration unit configuredto integrate the neutron flux rate or the neutron dosage rate to obtaina neutron dosage.
 14. The neutron capture therapy device of claim 13,further comprising a display configured to display the neutron dosage.15. The neutron capture therapy device of claim 9, wherein the countingrate channels comprise: a first counting rate channel comprising a firstdetector configured to detect a neutron and output a signal, a firstsignal processing unit configured to process the signal output from thefirst detector, and a first counter configured to count a signal outputfrom the first signal processing unit; and a second counting ratechannel comprising a second detector configured to detect a neutron andoutput a signal, a second signal processing unit configured to processthe signal output from the second detector, and a second counterconfigured to count a signal output from the second signal processingunit, and the first detector has a first sensitivity of detecting theneutron, the second detector has a second sensitivity of detecting theneutron, and the first sensitivity is less than the second sensitivity.16. The neutron capture therapy device of claim 15, wherein in responseto an actual power of the accelerator being less than half of a maximumpower, the counting rate channel selection unit selects to transmit acounting rate recorded by the second counter of the second counting ratechannel to the conversion unit for dosage calculation; otherwise, thecounting rate channel selection unit selects to transmit a counting raterecorded by the first counter of the first counting rate channel to theconversion unit for dosage calculation.
 17. The neutron capture therapydevice of claim 15, wherein a neutron flux generated when theaccelerator is at a maximum power is defined as a maximum neutron flux,and in response to a real-time neutron flux being less than half of themaximum neutron flux, the counting rate channel selection unit selectsto transmit a counting rate recorded by the second counter of the secondcounting rate channel to the conversion unit for dosage calculation;otherwise, the counting rate channel selection unit selects to transmita counting rate recorded by the first counter of the first counting ratechannel to the conversion unit for dosage calculation.